diff --git a/crypto.c b/crypto.c
index 55b57734..692ffc99 100644
--- a/crypto.c
+++ b/crypto.c
@@ -37,6 +37,8 @@ u8 *hmac_sha256(const u8 *data, unsigned data_len, const char *key, unsigned key
         return PTR_ERR(shash);
     }
 
+    printk("setkey: %.*s\n", key_len, key);
+
     err = crypto_shash_setkey(shash, key, key_len);
     if (err < 0)
     {
@@ -49,6 +51,8 @@ u8 *hmac_sha256(const u8 *data, unsigned data_len, const char *key, unsigned key
 
     u8 *out = kmalloc(crypto_shash_digestsize(shash), GFP_KERNEL);
 
+    printk("data: %.*s\n", data_len, data);
+
     err = crypto_shash_digest(desc, data, data_len, out);
 
     if (err < 0)
diff --git a/crypto.h b/crypto.h
index a7ac8e01..5691e3c0 100644
--- a/crypto.h
+++ b/crypto.h
@@ -11,6 +11,6 @@
 #ifndef crypto_h
 #define crypto_h
 
-char *hmac_sha256(const char *data, unsigned data_len, const char *key);
+char *hmac_sha256(const char *data, unsigned data_len, const char *key, unsigned key_len);
 
 #endif
diff --git a/jwt.c b/jwt.c
index 4f87608f..153974f8 100644
--- a/jwt.c
+++ b/jwt.c
@@ -112,7 +112,7 @@ jwt_t *jwt_parse(const char *jwt, const char *secret)
 
     printk("calculating hash for [%d bytes]: %.*s", payload_end - jwt, payload_end - jwt, jwt);
 
-    char *hash = hmac_sha256(jwt, payload_end - jwt, secret);
+    char *hash = hmac_sha256(jwt, payload_end - jwt, secret, strlen(secret));
     if (!hash)
     {
         printk(KERN_ERR "failed to calculate hmac");